Sodium Silicate

Sodium Silicate is an important chemical which can be considered either as a finished product or as a feedstock for manufacturing other finished products.

Sodium silicate is the generic name for a series of compounds derived from soluble sodium silicate glasses, with the formula Na2(SiO2)nO. A well-known member of this series is sodium metasilicate, Na2SiO3.
They are water solutions of sodium oxide (Na2O) and silicon dioxide (SiO2) combined in various ratios. Varying the proportions of SiO2 to Na2O and the solids content results in solutions with differing properties that have many diversified industrial applications.

Standard commercial grades of liquid sodium silicates range in weight ratio of SiO2 to Na2O from 1.6 to 3.3.
Sodium silicate with weight ratio SiO2/Na2O R=1.6÷2.5 is the base product of the silicate family.
It can be marketed as dried powder or as a concentrated solution and a solid content of about 40÷50°Bé. It is also the feedstock for producing other types of silicates.

Consito developed know-how and technologies for production plants of sodium silicate solutions & derivatives. In addition to liquid sodium silicates, our plants are able to produce silicates as powder, as well as metasilicates in granular anhydrous and pentahydrate forms.

We have some references for sodium silicate & allied products manufacturing.
Recently we supply complete engineering services for a well-known multinational company in Saudi Arabia for production of:

40.000 MTPY sodium silicate 2.5, 40÷50°Bé

3.000 MTPY sodium silicate 3.3, 38÷40°Bé

9.000 MTPY precipitated silica 95%

Production process

Sodium silicate with weight ratio SiO2/Na2O R=1.6÷2.5 is produced by direct reaction of siliceous sand with sodium hydroxide and water.
Sodium silicate is obtained by mixing raw materials at first into a dissolution vessel and then into a reactor in which the reaction between siliceous sand and sodium, hydroxide occurs.
Reactor is heated by saturated steam and works under pressure.
When the reaction time is spent the batch is transferred into a vessel and then filtered.

The silicate family can be summarized as follows:

Sodium Silicate solution 40÷50°Bé or 58÷60°Bé or powder, SiO2/Na2O ratio R=1.6÷2.5, by reaction of caustic soda and silica sand heated with steam (hydrothermal route). 58÷60°Bé grade is obtained by evaporation, powder by spray-drying. This kind of product is used in the production of detergents, metals, glass cleaning, silica gel, etc.

Sodium Silicate solution 38÷50°Bé or powder, SiO2/Na2O ratio R=3.3, by reaction of sodium silicate R=2.5 with precipitated silica (hydrothermal route). Power is obtained by spray-drying. This kind of product is used in the production of adhesives, sizing, coatings, titanium dioxide, etc.

Sodium Metasilicate Pentahydrate or granular anhydrous, by concentration & crystallization or drying of sodium silicate solution with R=1. Mainly used in soap and detergent production.

Zeolites, by reaction of sodium silicate with sodium aluminate. Mainly used in detergent production.

Operating data

Typical final product quality:

Sodium silicate with weight ratio SiO2/Na2O R=2 has the following composition:

Na2O=11.3%

SiO2=22.0%

Reaction times and solution purity depend on chemical and physical features of the sand.